Precession, basically is the change in the direction of earth's axisofrotation.
岁差，基本上是地球自转轴方向的改变。
2
What is the moment of inertia for rotationof a rod about this axis?
关于这个轴的,旋转动动量是多少？
3
The radius from the axisofrotation — - the axisofrotation is here — and the distance from here to here, though you may not think so, is about 15 meters.